Comparison of Passive DWDM and Active DWDM System
DWDM (dense wavelength division
multiplexing) technology is an ideal solution to address the capacity-hungry
issue, which can simply fall into two types, passive DWDM and active DWDM. To
greatly expand the bandwidth of the existing fiber system, both passive DWDM
and active DWDM systems are designed to multiplex different wavelengths for
carrying multiple signals over one single fiber. To better know the features of
these two DWDM systems, the following will intend to learn what are the passive
DWDM and active DWDM systems, and find their advantages and disadvantages.
Passive DWDM System Overview
Since there is no any active component
used in the passive DWDM system, the performance of the passive DWDM link only
depends on the optical budget of the DWDM transceivers used in the system.
That’s to say, the transmission distance the passive DWDM system supports can’t
be extended and is limited to the optical budget of the DWDM
transceivers. We can learn from the figure below that shows a common
passive DWDM system. Obviously, no active component like fiber amplifier and
DCM module, but a pairs of 20 channels DWDM Mux are used. This design allows
for high capacity transmission and makes capacity expansion possible. In short,
it is very suitable to deploy passive DWDM system in metro networks and high
speed and capacity communication lines.
Active DWDM System Overview
Unlike passive DWDM system, active DWDM
system can be composed of fiber amplifier, DWDM Mux, DWDM transceiver, DCM
module and OEO transponder, which can be also called transponder-based system.
Due to its active feature, it is easier to manage and control the optical
active DWDM network. Here offers the design of the active DWDM system for your
reference.
DWDM (dense wavelength division
multiplexing) technology is an ideal solution to address the capacity-hungry
issue, which can simply fall into two types, passive DWDM and active DWDM. To
greatly expand the bandwidth of the existing fiber system, both passive DWDM
and active DWDM systems are designed to multiplex different wavelengths for
carrying multiple signals over one single fiber. To better know the features of
these two DWDM systems, the following will intend to learn what are the passive
DWDM and active DWDM systems, and find their advantages and disadvantages.
Passive DWDM System Overview
Since there is no any active component
used in the passive DWDM system, the performance of the passive DWDM link only
depends on the optical budget of the DWDM transceivers used in the system.
That’s to say, the transmission distance the passive DWDM system supports can’t
be extended and is limited to the optical budget of the DWDM transceivers. We
can learn from the figure below that shows a common passive DWDM system.
Obviously, no active component like fiber amplifier and DCM module, but a pairs
of 20 channels DWDM Mux are used. This design allows for high capacity
transmission and makes capacity expansion possible. In short, it is very
suitable to deploy passive DWDM system in metro networks and high speed and
capacity communication lines.
Active DWDM System Overview
Unlike passive DWDM system, active DWDM
system can be composed of fiber amplifier, DWDM Mux, DWDM transceiver, DCM
module and OEO transponder, which can be also called transponder-based system.
Due to its active feature, it is easier to manage and control the optical
active DWDM network. Here offers the design of the active DWDM system for your
reference.
Active DWDM
In the active DWDM system, the
transponder usually utilizes short wave 850nm or long wave 1310nm to do the
optical-electrical-optical (OEO) DWDM conversion. When the long distance is
required in the active DWDM system, several EDFA fiber amplifiers will be
inserted along the active DWDM link. What should be noted is that the active
DWDM link can’t be extended infinitely, because the number of fiber amplifiers
for an active DWDM link is limited to the optical cable type, the channel
count, the data transmission rate of each channel, and permissible OSNR value,
etc.
Furthermore, the chromatic dispersion
occurring in the optical transmission also makes an influence on the
transmission distance of the active DWDM link. Hence, when designing the active
DWDM system, we should also take the permissible chromatic dispersion values of
the link into consideration. If needed, we can insert the dispersion
compensators (dcm modules) into the active DWDM link to enhance the optical
signals for a longer transmission.
Passive DWDM vs Active DWDM System
It is well known that the passive DWDM
system doesn’t need fiber amplifiers or dispersion compensators, which may
saves you a lot of time and money. Meanwhile, it is also very easy to deploy
due to the uncomplex installation. However, there are also several
disadvantages of passive DWDM system. Firstly, the scalability is not so good
as the active one. With the development of the passive DWDM system, more
passive devices are required. Meanwhile, the passive DWDM system will be
difficult to manage with the increasing of passive devices. What’s worse, if a
wavelength or connection needs to be changed in the link, the only option is to
take it out of link and disconnect the connection.
As for the active DWDM system, it can
multiplex more wavelengths over a single fiber pair. Hence, more bandwidth can
be provided by the active DWDM system. Furthermore, the active setups make the
optical system management easier. And you can directly change the wavelengths
or connections in the link without dropping connections. Finally, the active
DWDM system is more scalable than the passive one, which makes more wavelengths
to be multiplexed over the fiber. But one the other hand, there are also two
main disadvantages of active DWDM system. One is the high cost of the active
DWDM devices, and the other one is the complex installation.
In conclusion, the active DWDM system
can offer greater capacity and higher scalablity, while the the passive DWDM
system needs less cost and is easy to deploy. If the passive DWDM system meets
your need, you’d better not to choose the active one as it will cost you very
high. All in all, there is no the best, but the most suitable for your system.
Just choosing the most suitable DWDM for your system according to what your
network needs.
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